The invention relates to a device and method of using the device for providing a suspended volume of an agent without additional mixing.
Agents that do not persist in a suspended state and sediment must be resuspended prior to use. One example of an agent that must be resuspended prior to use is a pharmaceutical colloid, such as a contrast agent that is injected into a patient to enhance an imaging procedure. Contrast agents are used in various types of imaging including x-ray, magnetic resonance imaging (MRI), computed tomography (CT) and ultrasound (US). A contrast agent that comes out of suspension must be resuspended before placing the desired volume to be dosed into a delivery container such as a syringe. If there is a delay before the dose is injected into a patient, for example while preparing the patient or equipment, or if the infusion is extended, the agent must again be suspended before or during administration.
Resuspension of contrast agent requires mechanical manipulations, for example, removing a filled syringe positioned in an injector and remixing its contents. Additional remixing steps may delay a critical infusion time or, if remixing is omitted, the entire imaging procedure may have to be repeated due to suboptimal contrast obtained. Duplicate procedures not only put patients at increased risk and inconvenience, but are also cost- and time-inefficient. Even if the need to resuspend a single bolus injection is not prohibitive for a given procedure, repeated bolus injections or long term continuous infusions can become problematic due to the agent coming out of suspension during administration.
The loss of suspension for a contrast agent at any point in a delivery system to a patient, such as in a syringe and/or in the connecting tubing, severely limits the duration of continuous infusions or the time between intermittent injections. The need to initially resuspend the colloid or other type of agent, and to further suspend if the agent is not used shortly after resuspension, requires either time-consuming effort and vigilance by the user or the use of mechanical mixing devices. In any case, the need to resuspend an agent poses an additional step and a possible source of error in an imaging procedure.
The invention is directed to a method to control the rate at which a volume of an agent suspended in a fluid is delivered to a patient. The agent, provided in a device having a tubular network and inflow and outflow ports for a fluid to propel the agent, is divided into sub-volumes within the tubular network. By altering the flow to which the agent is exposed, for example, a laminar or nonlaminar flow, the rate at which the fluid is delivered is controlled. For example, laminar flow may be altered by changing the density, cross-sectional diameter, length, and/or pitch of the tubular network, and/or by symmetrically or randomly altering the radius of curvature. For example, the radius of curvature and/or density from the inflow port to the center of the device may progressively decrease, and the radius of curvature and/or density from the center of the device to the outflow port may progressively increase. Non-laminar flow may be altered by replacing a circular internal geometry of the tubular network with a non-circular geometry, in a symmetric or random manner and along part of or along the entire network path.
The invention is also directed to a method to control the rate at which a volume of an agent suspended in a fluid is delivered to a patient by providing the agent in a device having a tubular network containing sub-volumes of the agent. The device also contains inflow and outflow ports for fluid to propel agent from the network. The rate is controlled by altering a laminar flow of agent through the network by altering the network density, or by altering a nonlaminar flow of agent through the network by replacing a circular internal geometry of a network path with a non-circular geometry.
The invention is also directed to a suspension device that contains a tubular network providing at least one network path and containing sub-volumes of the agent, and has inflow and outflow ports for a fluid to propel agent from the network. The device has a cross-sectional internal geometrical configuration that may be of geometric shape and may be contiguous, non-contiguous, symmetrical or non-symmetrical along the length of the network. The tubular network may have a symmetrically altered radius of curvature, for example, the radius of curvature may increase from an inflow port to the center of the device and may decrease from the center of the device to an outflow port. The tubular network may be a compressible helix, either housed within a container such as a syringe or a network support, or placed in-line. The device may control the rate of agent delivery to a patient, and/or may enhance mixing of the agent.
The invention is also directed to a method and apparatus of decreasing escape of a gaseous agent contained within a suspension device, where the device is a network to contain sub-volumes of the agent and has inflow and outflow ports for a fluid to propel the agent from the network. In the method, one or more devices is provided within a container that is less permeable to the gaseous agent than the network. The apparatus is a container made of a material such as glass or a thick walled plastic such as polyvinyl chloride (PVC) or polypropylene that is less permeable to the gaseous agent than the network.
The invention is also directed to a suspension device for a volume of an agent that is a tubular network arranged in at least two parallel columns, where each column is independently operatively connected and contains sub-volumes of the agent, and inflow and outflow ports for a fluid to propel agent from the network. This embodiment of the device permits the user to adjust the network volume.
The invention is also directed to a method to deliver an agent that contains microbubbles of a pre-determined size. The agent is contained in a suspension device having a tubular network that contains sub-volumes of the agent, and inflow and outflow ports for a fluid to propel agent from the network. In the method, a force exerted on the microbubble-containing agent is altered by exposing the agent to a non-circular internal network geometry.
The invention is also directed to a method to alter a size distribution of microbubbles in a contrast agent injected into a patient by altering a flow rate of the agent between the agent source and an inflow line into the patient.
The invention is also directed to a suspension device for a volume of a contrast imaging agent, such as a microbubble-containing agent. The device is a compressible helical network, for example xc2xd foot to fifty feet in an uncompressed state, containing sub-volumes of the agent and with inflow and outflow ports for a fluid to propel agent from the network.
The invention is also directed to a method of providing a volume of a suspended agent to a patient by dividing the volume into sub-volumes, storing the sub-volumes in a network, mechanically mixing the agent in the network either before, during or after releasing the agent sub-volumes into a patient through a patient connector by providing a fluid under pressure through the network to propel the suspended agent.
These and other embodiments will become apparent in light of the following figures and detailed description.